Updated: 8 July 2026 – When it comes to installing a heat pump, the selection of materials and proper pipe diameters is When it comes to installing a heat pump, choosing the right pipe materials and pipe diameters is essential for system efficiency, reliability and long-term performance. Poor material selection or incorrect pipe sizing can reduce water flow, increase maintenance needs and affect the overall lifespan of the heating system.
This guide outlines the key factors to consider when selecting pipe materials and diameters for a successful heat pump installation.
Material Selection
Key Factors to Consider
Before selecting pipe materials for a heat pump system, several technical factors should be reviewed:
Ambient and outlet temperatures:
Pipes must be able to withstand low outdoor temperatures, especially in winter conditions, as well as high water outlet temperatures of up to 75°C in high-temperature heat pump applications.
Pressure resistance:
The pipe material must tolerate the operating pressure of the system without deforming, cracking or weakening over time.
Chemical compatibility:
The selected pipes should be compatible with the antifreeze solutions or water treatment products used in the system.
Risks of Poor Material Selection
Choosing the wrong pipe material can lead to leakage, reduced system performance, frequent maintenance and higher long-term costs. In some cases, unsuitable materials may also affect system safety and reliability.
Common Pipe Materials for Heat Pump Systems
Copper Pipes
Copper pipes are widely used in heating systems due to their excellent durability, corrosion resistance and thermal stability.
Main advantages:
- High stability for high-temperature systems
- Long lifespan, often exceeding 50 years
- Strong resistance to heat and corrosion
- Low maintenance requirements
- Natural antibacterial properties
The main disadvantage is the higher initial cost and the need for professional installation. However, for high-temperature residential heat pump systems, copper pipes are often a reliable long-term option.
PPR Pipes
PPR pipes offer a balance between cost, performance and ease of installation. They are generally more affordable than copper and easier to install, while still providing good resistance to heat and pressure.
However, PPR pipes may be less stable than copper in high-temperature applications, so their suitability should always be checked according to the system requirements.
PEX Pipes
PEX pipes are flexible, cost-effective and relatively easy to install. They are often used in lower-temperature heating systems and can be a practical solution in certain residential applications.
However, compared with copper, PEX may have lower stability in high-temperature systems and may require more careful evaluation depending on the operating conditions.
Pipe Diameter Selection
Choosing the correct pipe diameter is just as important as selecting the right material. The pipe diameter must support the required water flow rate of the heat pump and match the connection specifications of both the heat pump unit and the terminal equipment.
Key Factors to Consider
Connection requirements:
The selected pipe diameter should match the heat pump’s connection specifications and the requirements of the heating distribution system.
Rated water flow:
The pipe diameter must allow sufficient water flow. If the diameter is too small, the system may experience flow errors, reduced efficiency or unstable operation.
Risks of Incorrect Pipe Diameter
An incorrect pipe diameter can lead to insufficient water flow, system alarms, reduced heating performance and possible replacement of pipes or circulation pumps. This can increase both installation costs and future maintenance expenses.
General Recommendations
For a single-unit residential system, a DN25 inner diameter pipe is commonly recommended.
For cascade systems, the required pipe diameter may vary depending on the number of units, total water flow, installation layout and project-specific requirements. In these cases, the final pipe diameter should be confirmed by a qualified installer or system designer.
Conclusion
Installing a heat pump is a long-term investment, and correct pipe material and diameter selection play an important role in system performance. By choosing suitable materials, ensuring adequate water flow and following the manufacturer’s installation requirements, homeowners and installers can improve efficiency, reduce maintenance needs and support reliable operation for many years.
